The present invention relates generally to optical communications (e.g., wavelength-division multiplexing, optical code division multiple access (OCDMA), and add-drop devices). Also, the present invention is applicable to spectrophotometry, and reconfigurable optical filters.
In the field of optical communications there is presently a need for devices that can switch different wavelengths of light. For example, in wavelength-division multiplexed communications, often it is required for individual wavelengths to be connected to different ports (e.g. fibers or photodetectors). Also, optical add-drop multiplexers are needed to remove and then replace a single wavelength from an optical communication stream. These functions are especially difficult to implement if the device must be reconfigurable, or if the wavelengths to be manipulated are very close.
Also, optical communications can benefit from reconfigurable optical filters that have a broadly controllable optical response. Reconfigurable optical filters have a number of applications in the optical sciences and optical communications generally.
The present invention provides a reconfigurable optical device that can provide multiplexing, coding, spectrometer, and filtering functions.
The present invention provides an optical device having a partially reflecting, partially transmitting reflector, a movable mirror, and a light collimator. The movable mirror is spaced apart from and parallel with the reflector. The movable mirror can be moved to vary the spacing between the mirror and the reflector. The light collimator is disposed to project a light beam between the reflector and mirror at an oblique angle. An emergent beam is transmitted by the reflector each time the light beam reflects from the reflector. The emergent beams are spaced apart and preferably do not overlap.
The mirror can be a single large movable mirror. In this case, the light beam reflects from the mirror multiple times; each reflection is at a different position on the mirror because the light beam travels at an oblique angle.
Alternatively, the mirror can comprise an array (e.g. a linear array) of separately movable micromirrors. Each micromirror can move vertically to vary a spacing between the micromirror and the reflector. The micromirror array can have 1-1000 micromirrors, for example. The light beam can reflect at most once from each micromirror. Alternatively, the light beam can reflect 2 or 3 or more times from each micromirror.
The device can further comprise a lens for collecting the emergent beams and focusing them at a focal plane.
Alternatively, the mirror or micromirrors can comprise a controllable diffraction grating. The diffraction grating can vary the energy in the emergent beams.
The reflector can have a uniform or nonuniform reflectivity. The reflectivity of the reflector can be graded to provide a desired energy distribution among the emergent beams.